There is a >10 foot wide shoulder on that part of the road. Per the aerial photo.
https://maps.google.com/maps?q=10500+manchaca+road+south+austin+tx&hl=en&ll=30.16574,-97.828027&spn=0.001327,0.001206&sll=37.0625,-95.677068&sspn=55.586984,79.013672&t=h&hnear=10500+Manchaca+Rd,+Austin,+Texas+78748&z=20
Perfectly reasonable place to ride, assuming he was in the shoulder which I think is what the "bike lane" reference in the article means.
Not "pretty stupid" to ride there, unfortunately on any road at any time you can encounter a pretty stupid driver who can maim/kill you whether you are on a bike, on a motorcycle, or even in a car. When that pretty stupid driver flees the scene, he becomes a criminal and I truly hope he does jail time, and not a week or a month.